My boyfriend won't let me go out to visit his family and he is very secretive what is going on?

I ask him r u cheating he says no and gets angry and threatens to leave me also he goes his mums for like 4/5 hours at 11pm till 1am or 6/11pm we have only been together 3/months but I love him so much the thing is idc if he goes out but I also have illness which I can't control when left alone what do you think about it guys n girls?